As far as electrical and electronic goods are concerned, I've got two identical
Ever-Ready bike lights from the 80s, which I bought 20-odd years ago at a cycle-jumble. Both work perfectly, the one in the photo being on my 'Elephant bike', the commuting and shopping bike, the other being spare. They need an old-fashioned light-bracket to mount on a bike, but fortunately, Nelly has got one. (I think you can get retro-fittable mounts for modern bikes.)
Edit - the spare one was until recently on my Copenhagen Pedersen, mounted on the head tube with an old bracket taken from an ancient roadster, but it recently came loose and wouldn't tighten again. However, I've just found and ordered
this, at good old St John St Cycles, who always come up trumps, which bolts to the front fork boss, which fortunately the bike has got (they're for attaching front carriers to), so it (the lamp) will soon be back on the bike.